The present invention relates to the field of lift bed or lift deck vehicles and, more specifically, to heavy duty tractor-drawn lift deck trailers for transporting load holding pallet frame units. Each pallet frame unit has a ground engaging support structure enabling it to be picked up for transport or dropped off for storage without the need for additional equipment or personnel. This invention represents an improvement over the lift bed trailers disclosed in my copending application Ser. No. 315,437, filed Oct. 27, 1981, now U.S. Pat. No. 4,474,359 and in the copending application of David E. Gevers, Ser. No. 315,438, also filed Oct. 27, 1981 and now U.S. Pat. No. 4,474,526.
Trailers of this type are designed and built to carry heavy loads such, for example, as steel coils weighing approximately 60 tons. These loads are carried by the trailer with the lift deck and pallet frame unit in raised transport position. Heretofore, it has been necessary for the tractor driver to insert a long pin manually into the locking mechanism in order to secure the lift deck and load in transport position independently of the trailer hydraulic system. This requires the driver to reach under the lift deck when the latter is held in elevated position solely by the trailer hydraulic system. The driver is thus subjected to undue risk of injury in event of a sudden failure of the hydraulic system.